1. Field of the Invention
The present invention generally relates to a series-connected fan frame module and, more particularly, to a series-connected frame fan module that has a plurality of frames connected in series, in which axial disengagement and relative radial rotation of the frames are prevented.
2. Description of the Related Art
Referring to FIG. 1, Taiwanese Patent Number 569663 discloses a conventional series-connected fan frame module, which includes a first fan unit 81, a second fan unit 82 and two coupling members 83 and 84. The coupling members 83 and 84 couple the first fan unit 81 and the second fan unit 82 together in series. One of the coupling members 83 and 84 is in the form of engaging grooves while the other one is in the form of engaging tongues.
In the conventional series-connected fan frame module 8, the first fan unit 81 and the second fan unit 82 are mainly connected in series via the coupling members 83 and 84 (namely, the engaging grooves and engaging tongues). In addition, based on a central direction that extends through centers of the two impellers 85 installed in the first fan unit 81 and the second fan unit 82, the coupling members 83 and 84 not only can prevent the first fan unit 81 and the second fan unit 82 from axially disengaging from each other along the central direction, but also prevent the first fan unit 81 and the second fan unit 82 from relatively rotating with each other in a radial direction perpendicular to the central direction. However, since both the axial disengagement and relative radial rotation between the first fan unit 81 and the second fan unit 82 are prevented by the coupling members 83 and 84 only, the coupling members 84 tend to snap easily under vibrating pressure during rotation of the first fan unit 81 and the second fan unit 82. Furthermore, since the coupling members 83 and 84 are primarily used to prevent the axial disengagement between the first fan unit 81 and the second fan unit 82, the coupling members 83 and 84 cannot effectively prevent the relative radial rotation between the first fan unit 81 and the second fan unit 82 if a gap still exists between the coupling members 83 and 84 after they are engaged together. As a result, the relative radial rotation between the first fan unit 81 and the second fan unit 82 easily results, leading to a poor engaging effect between the first fan unit 81 and the second fan unit 82.
Referring to FIG. 2, a plurality of screws is used to replace the engaging grooves and tongues described above. In this case, the first fan unit 81 and the second fan unit 82 are coupled together in series by way of screws 86, which also prevents the axial disengagement and relative radial rotation between the first fan unit 81 and the second fan unit 82. However, in contrast to engaging the first fan unit 81 and the second fan unit 82 together, screwing the first fan unit 81 and the second fan unit 82 together causes more inconvenience during assembly.
Moreover, Taiwanese Patent Number M332744 discloses another type of conventional series-connected fan frame module. Referring to FIG. 3, the conventional series-connected fan frame module 9 includes a first housing 91 and a second housing 92. The first housing 91 includes a plurality of engaging members 911, and the second housing 92 includes a plurality of engaging holes 921. The engaging members 911 are inserted into the engaging holes 921 when the first housing 91 and the second housing 92 are coupled with each other in series. Based on this, the axial disengagement and relative radial rotation between the first housing 91 and the second housing 92 can also be prevented.
However, when the engaging members 911 are being engaged into the engaging holes 921, the engaging members 911 tend to easily snap off. More specifically, since the axial disengagement and relative radial rotation between the first housing 91 and the second housing 92 are prevented via the engaging members 911 only, the engaging members 911 tend to snap easily under vibrating pressure during rotation of the first housing 91 and the second housing 92.
Furthermore, similar problems arise for other conventional series-connected fan frame modules disclosed in the Taiwanese Patents numbered I285707, M278954, M285198, M285199, M333037 and M343076, so they are not described herein again for brevity.
In conclusion, even though the axial disengagement and relative radial rotation between a plurality of series-connected frames are provided in the various conventional series-connected fan frame modules described above, a weaker structural intensity or an inconvenient assembly of the conventional series-connected fan frame modules is still present.